62 lines
1.1 KiB
Bash
62 lines
1.1 KiB
Bash
#!/usr/bin/env zsh
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# Provide higer-order functions
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# usage:
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#
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# $ foo(){print "x: $1"}
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# $ map foo a b c d
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# x: a
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# x: b
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# x: c
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# x: d
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function map {
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local func_name=$1
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shift
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for elem in $@; print -- $(eval $func_name $elem)
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}
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# $ bar() { print $(($1 + $2)) }
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# $ fold bar 0 1 2 3 4 5
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# 15
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# -- but also
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# $ fold bar 0 $( seq 1 100 )
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function fold {
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if (($#<2)) {
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print -- "ERROR fold use at least 2 arguments" >&2
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return 1
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}
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if (($#<3)) {
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print -- $2
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return 0
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} else {
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local acc
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local right
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local func_name=$1
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local init_value=$2
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local first_value=$3
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shift 3
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right=$( fold $func_name $init_value $@ )
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acc=$( eval "$func_name $first_value $right" )
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print -- $acc
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return 0
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}
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}
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# usage:
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#
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# $ baz() { print $1 | grep baz }
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# $ filter baz titi bazaar biz
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# bazaar
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function filter {
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local predicate=$1
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local result
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typeset -a result
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shift
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for elem in $@; do
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if eval $predicate $elem >/dev/null; then
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result=( $result $elem )
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fi
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done
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print $result
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}
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